1. Field of the Invention
The present invention pertains to reclosable bags, including apparatus and methods for the manufacture thereof, and in particular to flexible bags having an open end with a metal strip on the bag adjacent the open end which, upon rolling the open end of the bag, is folded over to maintain a rolled closure thereof.
2. Description of the Prior Art
Over the years, many products have been packaged in flexible containers having releasable or resealable openings. Such closures are particularly popular for bulk-packaged items where the entire contents of the package are usually not consumed immediately upon the opening thereof. The following U.S. Patents, for example, disclose paper bags or envelopes having bendable metal tabs adjacent their open end to provide a closure: U.S. Pat. Nos. 488,783; 497,037; 1,210,699; 1,665,576; 2,093,976; 2,189,174; 2,635,788; 2,792,168; 2,973,131; 3,189,253; 4,593,408; and 4,679,701. Of these, some reclosable bags are directed to containers for food products.
For example, U.S. Pat. No. 2,635,788 is directed to a pouch for peanut butter having a bendable metal closure located adjacent a line of weakness whereat the bag may be torn open to gain access to the contents thereof. U.S. Pat. Nos. 2,973,131 and 3,189,253 are directed to bags of the tin-tie type for holding milk samples preparatory to making laboratory tests of the milk. The tin-tie closure members extend beyond the lateral sides of the bag to assist in grasping the bag and opening the metal closures which overlie both major sidewalls of the pouch and which have to be pried apart in order to gain access to the contents.
U.S. Pat. No. 4,593,408 is directed to a flexible package having a transversely extended opening to which a metal band is applied coextensive with the opening. The metal band is secured to one of the major surfaces of the pouch. A fold line extending along the longitudinal axis of the metal segment allows the metal segment to be bent over on itself to provide a releasable closure.
In addition to the above patents, U.S. Pat. No. 3,201,030 provides a different type of releasable closure wherein a plurality of wires are located in one wall of a bread container, extending along the longitudinal axis thereof. The wires extend into a flap overlying one end of the bread container. In use, the flap of the bread container is rolled upon itself as bread within the container is removed and the container subsequently resealed. The wires in the panel of the bread container help maintain the rolled configuration of its end flap.
Although different types of bendable, resealable closures have been provided, the need for an improved resealable closure still exists. Many of the resealable closures of the above-listed patents were invented prior to the advent of mass production, and especially prior to the advent of automated mass production. The containers for many kinds of products sold today, for example, food products, must be manufactured bulk, loaded with the food product, and sealed using totally automated mass production techniques, if a commercial advantage is to be maintained. Many of the resealable closures of the above-listed patents are totally unsuitable for such automated mass production.
The closures for containing food products or for other use in the food industry must meet rigorous standards not present at the time many of the containers of the above-listed patents were made. For example, cracks, crevices, and the like, even if located on the outside of a food container, should be eliminated if at all possible, since cavities and recesses might develop where bacteria and the like can reside. Further, many of the bendable, resealable closures listed above have exposed metal components which are subject to corrosion and other contamination over time. Accordingly, it is important that containers having bendable metal strips, and especially such containers used in the food industry have the metal strips completely encapsulated or sealed.
A large-scale food processing plant frequently coordinates a number of very expensive machinery components to form a production line. Components within the production line should, ideally, be carefully matched one to another, since the production rate of the line is limited by the slowest machine component thereof. Frequently, the individual components within a production line are revamped or replaced by updated equipment, and it is desirable that a particular modified machine component be compatible with the old component in terms of physical size, flow path configuration, in order to accommodate the continuous succession of products. For example, an improved container fabrication and sealing component should be compatible with existing bulk loading components, such that the products can be loaded within individual containers with a minimum of modification to peripheral equipment and with a minimal disruption in the production schedule of the plant.